This is v0.9 of PyECLib. This library provides a simple Python interface for
implementing erasure codes and is known to work with Python v2.6, 2.7 and 3.x.

To obtain the best possible performance, the underlying erasure code algorithms
are written in C. Please let us know if you have any other issues building or
installing (email: kmgreen2@gmail.com or tusharsg@gmail.com).

This library makes use of Jerasure for Reed-Solomon and provides its own flat
XOR-based erasure code encoder and decoder. Currently, it implements a
specific class of HD Combination Codes (see “Flat XOR-based erasure codes in
storage systems: Constructions, efficient recovery, and tradeoffs” in IEEE MSST
2010). These codes are well-suited to archival use-cases, have a simple
construction and require a minimum number of participating disks during
single-disk reconstruction (think XOR-based LRC code).

Note: bytes is a synonym to str in Python 2.6, 2.7.
In Python 3.x, bytes and str types are non-interchangeable and care
needs to be taken when handling input to and output from the encode() and
decode() routines.

Return the indexes of fragments needed to reconstruct “missing_fragment_indexes”:

def fragments_needed(self, missing_fragment_indexes)

Get EC Metadata

Return an opaque buffer known by the underlying library:

def get_metadata(self, fragment)

Verify EC Stripe Consistency

Use opaque buffers from get_metadata() to verify a the consistency of a stripe:

def verify_stripe_metadata(self, fragment_metadata_list)

Get EC Segment Info

Return a dict with the keys - segment_size, last_segment_size, fragment_size, last_fragment_size and num_segments:

def get_segment_info(self, data_len, segment_size)

Quick Start:

Standard stuff to install:

``Python 2.6``, ``2.7`` or ``3.x`` (including development packages) and ``argparse``.

This package includes c_eclib, which contains a few C libraries used by
PyECLib. These are built when running the PyECLib install (see below).

Install PyECLib:

$ sudo python setup.py install

Run test suite included:

$ (cd test && \
python run_tests.py && \
./ec_pyeclib_file_test.sh)

If all of this works, then you should be good to go. If not, send us an email!

If the test suite fails because it cannot find any of the shared libraries,
then you probably need to add /usr/local/lib to the path searched when loading
libraries. The best way to do this (on Linux) is to add ‘/usr/local/lib’ to: